Hi Raul,
On Thu, Aug 27, 2020 at 02:41:53PM -0600, Raul E Rangel wrote:
> The i8042_mutex must be held by writers of the AUX and KBD ports, as
> well as users of i8042_command. There were a lot of users of
> i8042_command that were not calling i8042_lock_chip/i8042_unlock_chip.
> This resulted in i8042_commands being issues in between PS/2
> transactions.
>
> This change moves the mutex lock into i8042_command and removes the
> burden of locking the mutex from the callers.
I think there is a benefit for allowing users issue a sequence of
commands to i8042 without interruptions, so I would prefer keeping
i8042_[un]lock_chip() in place.
Given that the issue you were observing was caused by i8042_port_close()
interfering with probing, maybe we could do something like this:
diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index abae23af0791..aff871001eda 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -344,6 +344,8 @@ int i8042_command(unsigned char *param, int command)
unsigned long flags;
int retval;
+ lockdep_assert_held(&i8042_mutex);
+
if (!i8042_present)
return -1;
@@ -364,6 +366,8 @@ static int i8042_kbd_write(struct serio *port, unsigned char c)
unsigned long flags;
int retval = 0;
+ lockdep_assert_held(&i8042_mutex);
+
spin_lock_irqsave(&i8042_lock, flags);
if (!(retval = i8042_wait_write())) {
@@ -411,6 +415,8 @@ static void i8042_port_close(struct serio *serio)
port_name = "KBD";
}
+ i8042_lock_chip();
+
i8042_ctr &= ~irq_bit;
if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR))
pr_warn("Can't write CTR while closing %s port\n", port_name);
@@ -422,6 +428,8 @@ static void i8042_port_close(struct serio *serio)
if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR))
pr_err("Can't reactivate %s port\n", port_name);
+ i8042_unlock_chip();
+
/*
* See if there is any data appeared while we were messing with
* port state.
Thanks.
--
Dmitry
